1. Field of the Invention
The present invention relates to a seat belt retractor, and more particularly, to a seat belt retractor capable of adhering a driver and a passenger to their seats by backwardly rotating a seat belt operating on vehicle collision.
2. Description of the Prior Art
A seat belt or an airbag is installed in a vehicle to safely protect a driver and a passenger from traffic accidents.
Such a seat belt is a basic safety device installed to operate upon vehicle accidents such as front collision, side collision, roll, and so on, to thereby maximally protect a driver and a passenger.
A widely used seat belt is a three-point safety belt constituted of a waist belt for protecting the waist of the passenger (hereinafter, including “driver”), and a shoulder belt for protecting the shoulder and the breast. A guide pulley is coupled with the shoulder belt, a retractor is installed at a center pillar of a vehicle to release or wind the belt, and the waist belt is fastened to a locker panel.
In addition, a tongue is inserted in a mid-portion of the belt, and the tongue can be locked to or released from a buckle fixed to a floor of the vehicle.
Further, the retractor for winding or releasing the seat belt is classified into a non-locking retractor (NLR), an emergency locking retractor (ELR), and a web locking retractor (WLR).
The non-locking retractor is locked after adjusting lengths of the shoulder belt and the waist belt. On the other hand, in the emergency locking retractor, the belt is freely retracted and rewound during stoppage or movement of the vehicle, and the belt is locked only when a vehicle collision causing abrupt deceleration occurs or when the belt is rapidly extracted.
In addition, in the web locking retractor, a clamp directly grips the belt upon vehicle collision to stop extraction of the belt, thereby preventing serious injury to the passenger due to abrupt forward movement of the passenger.
Meanwhile, Japanese Patent Laid-open Publication No. H8072671 discloses a “Seat Belt Retractor with Pretensioner attached thereto,” which will be described in brief.
The seat belt retractor having a pretensioner attached thereto includes a pretensioner for moving a rack, which can transmit a rotation torque to a winding shaft of the retractor, to rotate the winding shaft through a gas pressure upon collision of a vehicle in a direction of removing extraction of the seat belt using a pinion gear.
The pretensioner includes rotary drive members which are not connected to the winding shaft when the pretensioner is not operated and connected to the winding shaft when the pretensioner is operated to transit a rotation torque to the winding shaft a pinion gear for dependently rotating the rotary drive members using rotation of the pinion gear normally meshed with the rack, and a driven gear mechanism installed between the rotary drive members.
In addition, Japanese Patent Laid-open Publication No. H8-133015 discloses a “Seat Belt Retractor with Pretensioner attached thereto,” which will be described in brief.
The seat belt retractor includes a pretensioner for driving a rotary drive member, which can transmit a rotation torque to a winding shaft, to rotate the winding shaft in a direction of removing extraction of a seat belt using rotation thereof upon collision of a vehicle.
The pretensioner includes a cam surface in which a sleeve installed at the winding shaft and the rotary drive member relatively rotatably supported around a shaft center define a wedgewise space between the rotary drive shaft and the outer periphery of the sleeve, a drive force transmission member installed in the wedgewise space and movable in a sleeve coupling direction, and a support means for restricting movement of the drive force transmission member in the sleeve coupling direction.
The support means is engaged with a retractor body by interposing a breakable connection means in which a breakable part is formed at a portion thereof except a sliding surface when the rotary drive member is rotated, the rotary drive member is rotated to a certain angle upon collision of a vehicle to engage the drive force transmission member with the sleeve and the cam surface, and then, the breakable part of the support means is broken to release engagement of the support means with the retractor body.
Meanwhile, Japanese Patent Laid-open Publication No. H11-222100 discloses a “Seat Belt Retractor,” which will be described in brief.
The seat belt retractor, which includes a winding drum for winding a webbing and a spindle shaft having one end functioning as a torsion bar coupled to the winding drum in a relatively non-rotatable manner, to absorb energy using distortion of the spindle shaft upon emergency of a vehicle, is characterized in that the seat belt retractor includes a fastening mechanism for allowing distortion of the spindle shaft until a rotation amount of the distortion of one end of the spindle shaft adjacent to the other end reaches a predetermined value upon emergency of the vehicle, and fastened to prevent relative rotation between the other end proximity part of the spindle shaft and the winding drum when a rotation amount of the distortion reaches the predetermined value.
In addition, Japanese Patent Laid-open Publication No. 2000-289571 discloses a “Webbing Winding Device,” which will be described in brief.
The webbing winding device includes a frame supported at a vehicle body, a winding shaft rotatably supported by the frame and winding a webbing for restricting a passenger using a bias force in a layered manner, and a lock means for preventing rotation of the winding shaft in a webbing extraction direction upon abrupt deceleration of a vehicle.
The lock means includes a first lock part concentrically disposed with respect to the winding shaft to be rotated along the winding shaft and preventing rotation of the winding shaft in the webbing extraction direction upon abrupt deceleration of the vehicle, and a plastic second lock part concentrically disposed with respect to the winding shaft to be integrally rotated with the winding shaft and causing relative rotation between the second lock part and the first lock part when the rotation in the webbing extraction direction of the first lock part is prevented.
In addition, the lock means further includes a third lock part formed of a single body having a high strength lock gear movably supported by the second lock part in a radial direction and moving outward in the radial direction when a relative rotation between the first lock part and the second lock part occurs, and a fourth lock part having a high strength lock gear installed at the frame and meshed with the lock gear of the third lock part when the third lock part moves outward in the radial direction.
The lock means further includes a guide part using repulsion generated when the lock gear of the third lock part is engaged with the lock gear of the fourth lock part to move a predetermined part of the second lock part in a direction opposite to the engagement position and plastically deform the predetermined part to be directly engaged with the fourth lock part.
Further, Japanese Patent Laid-open Publication No. 2000-289572 discloses a “Webbing Winding Device,” which will be described in brief.
The webbing winding device includes a winding shaft winding a webbing for restricting a passenger using a bias force in a layered manner, a cylindrical base member constituting a portion of a lock means mounted in a recess formed in a shaft center end of the winding shaft and locking rotation in a webbing extraction direction of the winding shaft upon abrupt deceleration of a vehicle, and an anti-slip-off member press-fitted between an outer periphery of the base member and an inner periphery of the winding shaft in both radial directions of the base member in a state that the base member is mounted in the recess of the winding shaft.
Furthermore, Japanese Patent Laid-open Publication No. 2000-302012 discloses a “Webbing Winding Device,” which will be described in brief.
The webbing winding device includes a winding shaft to which a base end of a long strip-shaped webbing belt for restricting a passenger's body is fixed and biased in a direction winding the webbing belt, a pretensioner for rotating the winding shaft in the winding direction under a predetermined condition, a bearing means disposed on a shaft having an inner diameter larger than an outer diameter of the winding shaft having an inner periphery into which the winding shaft is inserted, and a projection projecting from one of the inner periphery of the bearing means and the outer periphery of the winding shaft toward the other and contacting the other at a very small area in comparison with the area of the other opposite to the one.
In addition, Japanese Patent Laid-open Publication No. 2000-302013 discloses a “Pretensioner,” which will be described in brief.
The pretensioner is integrally formed with a webbing winding device for winding a webbing for restricting a passenger on a winding shaft in a layered manner to rapidly rotate the winding shaft in a webbing winding direction to a predetermined extent using a rack/pinion type drive mechanism upon rapid deceleration of a vehicle. The drive mechanism includes a piston movably disposed in a cylinder in an axial direction and having a rack bar to be moved upon rapid deceleration of the vehicle, and a pinion disposed to be meshed with a rack gear of the piston and directly connected to a shaft end of the winding shaft through the medium of a clutch connected to the winding shaft upon rapid deceleration of the vehicle.
Meanwhile, Japanese Patent Laid-open Publication No. 2000-302008 discloses a “Webbing Winding Apparatus,” which will be described in brief.
The webbing winding apparatus includes a frame having a pair of rectangular plates opposite to each other, and a winding shaft, to which one end of an elongated strip shape of webbing belt is fixed to restrain a passenger, for biasing the webbing belt in a winding direction, and supported at both sides of a portion of the fastened webbing belt by the pair of rectangular plates in an axial direction.
In addition, the webbing winding apparatus has a fixing part fixed to a vehicle body and connecting the respective lateral ends of the pair of rectangular plates. In addition, a connection part having a plurality of hexagonal parts is installed at the frame. The plurality of hexagonal parts have empty parts or thin parts, respectively, such that the plurality of hexagonal parts are continuously or intermittently arranged in a tension direction applied between the winding shaft and the pair of rectangular plates when the webbing belt is extracted, and simultaneously aligned parallel to each other depending on the tension direction.
Although the webbing winding apparatus has advantages in that uniform tension is applied to the frame connection part in the tension direction when the webbing belt is extracted and elastic deformation of the connection part is uniformized, since the flame is deformed due to the tension applied to the frame, the webbing winding apparatus cannot be normally operated.
In addition, Japanese Patent Laid-open Publication No. 2000-309249 discloses a “Safety Belt Retractor,” which will be briefly described below.
The safety belt retractor includes a spool rotatably biased in one direction to wind a webbing, a ratchet wheel rotated with the spool, and an emergency lock mechanism meshed with the ratchet wheel in response to emergency detection by an inertia detection means and having a pawl for locking the spool using the corresponding ratchet wheel.
In addition, a torsion bar is installed between the spool and the ratchet wheel. One end of the torsion bar is coupled to the spool, and the other end of the torsion bar is coupled to the ratchet wheel. Therefore, the torsion bar is twisted when the webbing extraction force is applied during operation of the emergency lock mechanism, thereby absorbing impact.
Further, the torsion bar has a polygonal coupling part coupled to the ratchet wheel, and the ratchet wheel has a polygonal fastening hole to which the polygonal coupling part is fastened. A rib-shaped projection is formed at an inner surface of the polygonal fastening hole in an axial direction of the torsion bar to thereby bias the torsion into the fastening hole in a direction that the torsion bar is rotated during extraction of the webbing, in order to press fit the surfaces of the torsion bar and the ratchet wheel to each other in the direction that the torsion bar is rotated.
Although the seat belt retractor has an advantage in that there is no assembly error since the torsion bar and the ratchet wheel are assembled at a predetermined angle, because both ends of the torsion bar have a polygonal shape it is difficult to manufacture the torsion bar, and thus manufacturing cost may increase.
In addition, Japanese Patent Laid-open Publication No. 2003-146183 discloses a “Webbing Winding Device,” which will be described in brief.
The webbing winding device includes a spool for winding a webbing for restricting a passenger using a bias force in a layered manner, an energy absorption member concentrically connected to the spool to be rotated together with the spool and allowing a predetermined amount of rotation of the spool deformed depending on application of a load more than a predetermined value in a webbing extraction direction through the medium of the spool in a state that the rotation in the webbing extraction direction is restricted, a lock means partially and concentrically inserted between the energy absorption member and the spool and stopping rotation of the energy absorption member in the webbing extraction direction upon abrupt deceleration of a vehicle, and an anti-slip-off-member inserted between a portion of an outer periphery of the lock means and an inner periphery of the spool in a direction perpendicular to the shaft and assembled therebetween, and applying both a compression load in a thrust direction and a compression load in a radial direction between a portion of the lock means and the spool.
In addition, Japanese Patent Laid-open Publication No. 2003-212085 discloses a “Seat Belt Retractor,” which will be described in brief.
The seat belt retractor includes a “C” shaped housing body having a pair of opposite side plates having through-holes, respectively, a shaft body rotatably connected to a winding drum, on which a webbing is wound, and passing through the through-holes to be rotatably supported by the side plates and rotatably biased in a webbing extraction direction, an emergency lock mechanism for stopping rotation of the shaft body in the webbing extraction direction, and first and second lock start mechanisms for operating the emergency lock mechanism.
The emergency lock mechanism includes a lock gear formed at an inner periphery of one of the through-hole of the housing body, a lock base mounted inside the lock gear to be rotated with the lock gear, and a pawl located at the lock base and meshed with the lock gear projecting from an outer periphery of the lock base.
The emergency lock mechanism includes a lock clutch relatively rotatably mounted on the shaft body adjacent to the outer periphery of the lock base, mounted to be synchronously rotated with the lock base in a state of being biased in the webbing extraction direction, having a ratchet wheel part having a ratchet at its outer periphery, slidably guiding a link pin projecting from the pawl through relative rotation with respect to the lock base, and having a projection guide groove projecting from the pawl.
In addition, the first lock start mechanism includes an inertia mass body swung in response to abrupt variation in acceleration of a vehicle, and a sensor lever engaged with the latchet of the latchet wheel to stop rotation of the lock clutch body depending on swing of the inertia mass body.
Further, the second lock start mechanism includes a cover body covering portions of the first and second lock start mechanisms, disposed inside a ratchet wheel, and having a coupling inner periphery wall having inner periphery teeth projecting therefrom, and a lock arm rotatably supported by one side of the lock clutch body with respect to the cover body and stopping rotation of the lock clutch coupled to an internal gear of the inner periphery due to rotation delay in a direction opposite to the bias direction caused by abrupt rotation of the lock clutch body biased in a direction opposite to the separation of the internal gear from the inner periphery.
Meanwhile, Japanese Patent Laid-open Publication No. 2003-212086 discloses a “Safety Belt Retractor,” which will be described in brief.
Such a safety belt retractor includes an emergency lock start device for starting a lock mechanism reacting to rapid variation in acceleration of a vehicle and stopping extraction of a webbing. The emergency lock start device includes a box-shaped holder having a concave part formed at its bottom surface, an inertia mass disposed in the concave part of the holder and swinging in response to acceleration larger than a predetermined value, and a sensor lever for rotatably supporting a shaft part installed at one end thereof in the holder and operating the lock mechanism rotated around an axial center of the shaft part depending on swing of the inertial mass. A guide groove is formed at an outer periphery of the shaft part of the sensor lever, and a rotation restriction projection projects from the outer periphery to be inserted into the guide groove of the holder and restricts a rotation range of the sensor lever.
Further, Japanese Patent Laid-open Publication No. 2003-335217 discloses a “Safety Belt Retractor,” which will be described in brief.
The safety belt retractor includes a housing having a pair of side plates, a winding shaft rotatably supported between the side plates of the housing and rotatably biased in a webbing winding direction, and a pretensioner mechanism attached to one side plate of the housing to rotate the winding shaft in the webbing winding direction and wind the webbing upon rapid deceleration of a vehicle.
The pretensioner mechanism includes a gas generator for generating a gas, a cylinder having one end on which the gas generator is mounted and the other end installed at an outer surface of the one side plate of the housing at its one side, and a pinion gear interlocked with the winding shaft to be rotatably supported by the winding shaft.
In addition, a piston is installed at a base end to be movably accommodated in the cylinder to be driven by a gas pressure, and a rack is formed at a front end of the piston to be meshed with the pinion gear. The rack is meshed with the pinion gear depending on the compression driving of the piston to rotate the winding shaft in the winding direction.
Further, the retractor includes a cover body for forming a movement guide path of the rack disposed on an extension line of the other end of the cylinder and projecting from the other end of the cylinder, a first adhesion part installed at the one side plate of the housing to cover an opening at the other side of the cylinder part in a manner adhered to the piston, and a second adhesion part installed at the cover body to cover the opening of the other side of the cylinder in a manner adhered to the piston.
In addition, Japanese Patent Laid-open Publication No. 2003-341473 discloses a “Seat Belt Retractor,” which will be briefly described below.
The seat belt retractor includes a winding drum on which a webbing is wound, a torsion bar inserted into the winding drum and coupled to one end of the winding drun at its one end in a non-relative rotation manner and simultaneously biased in a webbing winding direction, and an emergency lock mechanism operated in an emergency and stopping rotation of the other end of the torsion bar in the webbing extraction direction.
In addition, the seat belt retractor includes a winding part adjacent to the other end of the winding drum, a plate coupled to the other end of the torsion bar in a non-relative rotation manner, and a wire coupled to the plate at its one end and disposed along a curved path installed at the middle part of the other end surface of the winding drum.
Further, in a vehicle emergency, when an extraction force more than a predetermined value is applied to the webbing after operation of the emergency lock mechanism, the torsion bar absorbs distortion and impact energy due to extraction resistance of the wire from the curved path by relative rotation between the plate and the winding drum.
The wire is extracted from the curved path by the relative rotation between the plate and the winding drum, and an outer diameter of the winding part of the plate, on which the wire is wound, is twisted to reduce extraction resistance of the wire being gradually varied from a start time.
Although the seat belt retractor has an advantage in that the wire absorbs distortion of the torsion bar, since a curved path should be formed at the winding drum, the manufacturing process is difficult and therefore manufacturing cost of the retractor is also increased.
In addition, Japanese Patent Laid-open Publication No. 2004-1777 discloses a “retensioner,” which will be described in brief.
The pretensioner is integrally formed with a webbing winding device for winding a webbing for restricting a passenger on a winding shaft in a layered manner to rapidly rotate the winding shaft in a webbing winding direction to a predetermined extent using a rack/pinion type drive mechanism upon rapid deceleration of a vehicle.
The drive mechanism includes a piston movably disposed in a cylinder in an axial direction and having a rack bar to be moved upon rapid deceleration of the vehicle, and a pinion disposed to be meshed with a rack gear of the piston and directly connected to a shaft end of the winding shaft through the medium of a clutch connected to the winding shaft upon rapid deceleration of the vehicle.
The pinion includes a gear part having a pinion gear meshed with the rack gear, and a clutch part integrally formed with the gear part in a concentric manner and having the clutch formed at an inner periphery thereof.
Further, Japanese Patent Laid-open Publication No. 2004-175279 discloses a “Pretensioner Device,” which will be described in brief.
The pretensioner device includes a piston movable by operation of a gas generation means upon abrupt deceleration of a vehicle, and a winding shaft, on which a webbing for restricting a passenger is wound in a layered manner, rapidly rotated in a webbing extraction direction to an extent corresponding to a moving stroke of the piston.
A clutch mechanism of the pretension includes a cylindrical sleeve inserted into one axial end of the winding shaft in a relatively non-rotatable manner and having a knurled surface formed at its periphery, a plate-shaped base part concentrically installed on the sleeve, a clutch member including a plurality of lift parts relatively rotatably installed at the sleeve and having a coupling surface opposite to the knurled surface in a normal state to be coupled to the knurled surface, and a clutch operation member disposed to be clutched to the clutch member to operate the gas generation means upon abrupt deceleration of a vehicle, moving the piston to rotate the winding shaft in a webbing winding direction, and deforming the lift part in a direction in which the coupling surface is coupled to the knurled surface.
In addition, an arm part is installed to be supported on both sides of the base part and support the lift part by forming a cutout part, a slit part or an aperture at the base part, and moves the lift part in a coupling direction of the sleeve within a formation range of the cutout part, the slit part or the aperture.
In addition, Japanese Patent Laid-open Publication No. 2006-213112 discloses a “Pretensioner Device.” The pretensioner device has a first protrusion protruding from the other side of a cam part in a peripheral direction thereof, and a meshing claw of a clutch plate has a second protrusion formed so that one circumferential cross-section of the cam part opposes the first protrusion.
As described above, the second protrusion formed at the clutch plate may be broken, and its assembly is very difficult and time-consuming.
In addition, assembly of the seat belt retractor requires much assembly time, thereby decreasing assembly efficiency. Further, complexity of the parts constituting the seat belt retractor makes it difficult to manufacture the seat belt retractor, thereby increasing manufacturing cost. Furthermore, when the webbing of the seat belt retractor is to be rewound, it may not successfully operate, and a passenger may misconceive that the seat belt could be out of order.
Further, in the conventional arts, the respective components have complicated shapes to increase the complexity of the manufacturing process thereof, and an increase in the number of assembly processes of the seat belt retractor results in a long assembly time. As a result, manufacturing cost of the seat belt retractor is also increased.
Furthermore, since each component constituting the seat belt retractor is heavy, the total weight of the seat belt retractor is increased.